Illumination device, design method of illumination device, and design device of illumination device

Abstract

An illumination device, which projects a projection pattern including information onto a projection plane, includes a light source that emits a coherent light beam, and a diffractive optical element that diffracts the coherent light beam from the light source and projects the projection pattern. The diffractive optical element has a diffraction characteristic that allow an observer who sees the projection pattern from a viewpoint position in a first line-of-sight direction based on a position and a direction of the diffractive optical element, to visually recognize the information with a predetermined size, a predetermined shape and a predetermined inclination angle.

1 - 22 . (canceled) 
     
     
         23 . An illumination device that projects a projection pattern including information onto a projection plane, comprising:
 a light source that emits a coherent light beam; and   a diffractive optical element that diffracts the coherent light beam from the light source and projects the projection pattern;   wherein the diffractive optical element has a diffraction characteristic that allow an observer who sees the projection pattern from a viewpoint position, to visually recognize the information in a plane that is non-parallel to the projection plane.   
     
     
         24 . The illumination device according to  claim 23 , wherein
 a ratio of a certain part of the information actually observed by the observer with respect to a corresponding part of the projection pattern on the projection plane is decreased, as a distance from the viewpoint position of the observer to the certain part of the projection pattern increases.   
     
     
         25 . The illumination device according to  claim 23 , wherein
 a radiant intensity of a coherent light beam from the illumination device toward a certain point of the projection pattern is increased, as a distance from the illumination device to the point is longer.   
     
     
         26 . The illumination device according to  claim 23 , wherein a minimum value X min  of radiances of the projection pattern when the projection pattern is observed from the viewpoint position, a maximum value X max  of the radiances, and an average value X ave  of the radiances satisfy following two expressions (1) and (2):
   ( X   max   −X   ave )/ X   ave ≤0.4   expression (1) and
     ( X   ave   −X   min )/ X   ave ≤0.4   expression (2).
   
     
     
         27 . The illumination device according to  claim 23 , wherein a minimum value Y min  of irradiances at respective points on the projection pattern, a maximum value Y max  of the irradiances, and an average value Y ave  of the irradiances satisfy following two expressions (3) and (4):
   ( Y   max   −Y   ave )/ Y   ave ≤0.4   expression (3) and
     ( Y   ave   −Y   min )/ Y   ave ≤0.4   expression (4).
   
     
     
         28 . The illumination device according to  claim 23 , comprising a shaping optical system that collimates the coherent light beam emitted from the light source,
 wherein the diffractive optical element diffracts the coherent light beam collimated by the shaping optical system and projects the projection pattern.   
     
     
         29 . The illumination device according to  claim 28 , wherein
 the shaping optical system regulates a traveling direction of the coherent light beam emitted from the light source so as to suppress blurring of the projection pattern.   
     
     
         30 . A design method of an illumination device comprising:
 a step of setting observation-condition information including a viewpoint position and a line-of-sight direction of an observer, and including information to be observed by the observer;   a step of calculating, based on the observation-condition information, projection-condition information including a position in a projection plane onto which a projection pattern is projected, and a shape and a size of the projection pattern on the projection plane; and   a step of calculating, based on the projection-condition information and a position of an illumination device that projects the projection pattern onto the projection plane, illumination-condition information including a radiant-intensity distribution of a coherent light beam emitted from the illumination device toward the projection plane.   
     
     
         31 . The design method according to  claim 30 , wherein
 the illumination device is provided with a light source that emits the coherent light beam, and a diffractive optical element that diffracts the coherent light beam from the light source and projects the projection pattern, and   the design method further comprises a step of designing a diffraction characteristic of the diffractive optical element based on the illumination-condition information.   
     
     
         32 . The design method according to  claim 31 , wherein
 the diffraction characteristic is designed such that, when the projection pattern is seen from the viewpoint position in the line-of-sight direction, the information determined by the observation-condition information is visually recognized.   
     
     
         33 . The design method according to  claim 30 , wherein
 in order that, when the projection pattern is seen from the viewpoint position in the line-of-sight direction, the information is visually recognized in a plane that is non-parallel to the projection plane, the observation-condition information includes information related to a direction of the non-parallel plane.   
     
     
         34 . The design method according to  claim 30 , wherein
 the step of calculating the projection-condition information calculates a shape and a size of the projection pattern, such that the shape and the size of the projection pattern differ depending on a distance from the viewpoint position to respective points on the projection pattern.   
     
     
         35 . The design method according to  claim 30 , wherein
 the observation-condition information includes a radiance distribution which is set such that radiances of the projection pattern are uniform, when the projection pattern is observed from the viewpoint position.   
     
     
         36 . A design device of an illumination device comprising:
 an observation-condition setting unit that sets observation-condition information including a viewpoint position and a line-of-sight direction of an observer, and including information to be observed by the observer;   a projection-condition calculation unit that calculates, based on the observation-condition information, projection-condition information including a position in a projection plane onto which a projection pattern is projected, and a shape and a size of the projection pattern on the projection plane; and   an illumination-condition calculation unit that calculates, based on the projection-condition information and a position of an illumination device that projects the projection pattern onto the projection plane, illumination-condition information including a radiant-intensity distribution of a coherent light beam emitted from the illumination device toward the projection plane.   
     
     
         37 . The design device according to  claim 36 , wherein
 the illumination device is provided with a light source that emits the coherent light beam, and a diffractive optical element that diffracts the coherent light beam from the light source and projects the projection pattern, and   the design device further comprises a diffraction-characteristic design unit that designs a diffraction characteristic of the diffractive optical element based on the illumination-condition information.   
     
     
         38 . The design device according to  claim 37 , wherein
 the diffraction-characteristic design unit designs the diffraction characteristic such that, when the projection pattern is seen from the viewpoint position in the line-of-sight direction, the information determined by the observation-condition information is visually recognized.   
     
     
         39 . The design device according to  claim 36 , wherein
 in order that, when the projection pattern is seen from the viewpoint position in the line-of-sight direction, the information is visually recognized in a plane that is non-parallel to the projection plane, the observation-condition information includes information related to a direction of the non-parallel plane.   
     
     
         40 . The design device according to  claim 36 , wherein
 the projection-condition calculation unit calculates a shape and a size of the projection pattern, such that the shape and the size of the projection pattern differ depending on a distance from the viewpoint position to respective points on the projection pattern.   
     
     
         41 . The design device according to  claim 36 , wherein
 the observation-condition information includes a radiance distribution which is set such that radiances of the projection pattern are uniform, when the projection pattern is observed from the viewpoint position.